ACSI2STM understanding or in my case Lack of

[Vipersan]

I really needed to get my head around this concantinate and split idea of constructing a physical binary image that can be flashed to a 27c4096 for use in the TOS switcher..
and yes my brain hurts....but I think I now understand.
I searched ..found and downloaded 2 x 256k binary files .img extensions.
etos256uk
tos206uk
re-labled them A.img and B.img for convenience
Popped the files in a folder called simply Z again ..for convenience (easy access using command function in windows)
Entered directory X in CMD and using this expression
Copy /B A.img + B.img C.img
The result was a concatenated C.img 512k
I aint much good if I dont have a GUI ...
So I searched online for byte swap program to use....but discovered this in the process.
An on-line byte swap util created by one of my favourite youtubers Bits und Bolts
https://bitsundbolts.com/2025/08/13/bios-tools/
well worth taking note oi imo
Anyhoo ..dropped in the 512k C.img and pushed go..
It pruduced 2x 256k files which I assume are now byte swapped..
and the webpage has a merge tool ...into which I placed these (byte swapped) images ..and hit go
I wasn't abolutely sure of the result so did it again with the A swapped and swapped B reversed ...
I wasn't sure which was Hi and Lo at this point so created 2x512k images with the merge tool
so both variations covered ?
but I am assuming one of these 512k files can be programmed to a 27c4096..I have 5 on order..but they are coming from china (yep ..risky I know..but they were very inexpensive ...so fingers crossed)
Just hope my luck holds ...after hitting the jackpot twice already with DMA chips and a cmos cpu
I also have a TL866 ..ZIF to PLCC adapter on order...
I hope it doesn't need modiying..
but that's a bridge I'll cross when I reach it.
Can anyone see a flaw in my logic process for creating a suitable binary image for the TOS chip I'm hoping to make
Please let me know asap
cheers

[chakobsa]

If you just want to try different Atati TOS roms including EmuTOS I recommend Sidecartridge TOS emulator.

You can switch ROM in seconds via software.

There is also an Amiga 500 version which is also excellent.

[Vipersan]

If you just want to try different Atati TOS roms including EmuTOS I recommend Sidecartridge TOS emulator.

You can switch ROM in seconds via software.

There is also an Amiga 500 version which is also excellent.

Thanks for that chakobsa
..added that to my to-do investigation list..

[alexh]

I do have the option to switch as I bought a small pcb kit and chip from EXXOS. currently TOS1.62 (or 2.06) ..but how easy would it be to substitute a different version ..say EMUTOS instead of one of the TOS versions ?

I really needed to get my head around this concatenate and split idea of constructing a physical binary image that can be flashed to a 27c4096 for use in the TOS switcher..

It's not something I've seen Exxos discuss but I imagine that it is linear? e.g. you append one emulator ROM 256KByte image to the end of another and then write to the EPROM. If the ROM images are less than 256KByte then they might need padding.

I searched ..found and downloaded 2 x 256k binary files .img extensions.
etos256uk
tos206uk
re-labelled them A.img and B.img for convenience
Popped the files in a folder called simply Z again ..for convenience (easy access using command function in windows)
Entered directory X in CMD and using this expression
Copy /B A.img + B.img C.img
The result was a concatenated C.img 512k

This is what I would have done.

So I searched online for byte swap program to use....but discovered this in the process.
An on-line byte swap util created by one of my favourite youtubers Bits und Bolts
https://bitsundbolts.com/2025/08/13/bios-tools/
well worth taking note oi imo
Anyhoo ..dropped in the 512k C.img and pushed go..
It produced 2x 256k files which I assume are now byte swapped..

Why is byte-swapping necessary? The 27C4096 ROM is a single 16-bit ROM. It should take the two emulator ROMs concatenated without byte swapping. But this is not my area of expertise.

[Vipersan]

[/quote]
Why is byte-swapping necessary? The 27C4096 ROM is a single 16-bit ROM. It should take the two emulator ROMs concatenated without byte swapping. But this is not my area of expertise.
[/quote]

I asked myself the same question Alex...
..I did this byte swap simply because this was what I had seen and read...was neccessary.
I was hoping others who had done this before might be able to confirm..and perhaps explain why.

It sort of makes sense when using 2x chips..but less sense when a single chip.
If it is neccessary ..I can only conclude this must be a requirement of the cpus addressing protocol.
rgds

[alexh]

It's not my area of expertise. It might be due to the tools being for little endian and 68000 being big endian?

Try it swapped, if it doesn't work try it not swapped.

[Vipersan]

It's not my area of expertise. It might be due to the tools being for little endian and 68000 being big endian?

Try it swapped, if it doesn't work try it not swapped.

You could very well be correct Alex.

...which is why I have created 2 versions..
one of them should work..

That said..I prefer to understand the process than just doing it blind..

[Vipersan]

My Adapter should be here tomorrow...rather than buy one for my TL866...I ordered an ADP-054 for my GQ-4x4
It wasn't cheap but it does expand the range of devices I can read/program on account it expands the zif to include a 40 dip and a 48 pin dip plus it has 2 x 44 pin plcc ..presumably for both..eprom and micro.
I just hope the plcc chips I ordered are up to snuff..
we shall see.

[Vipersan]

The adapter has arrived but of course Im still waiting for those chips...which could be weeks away.
..and no guarantee they are any good...
they are almost certainly used 'pulls' ...but will they be any good ?
Possibly fake..
possibly faulty..
may even have bent pins which is often the case with aggressive treatment.
I dont suppose a forum member has one they could sell me so I can at least try out the ADP054 adapter ?
PLCC 27C4096 UV erasable
Didn't see any for sale on Exxos shop or I would have placed an order immediately.

[rubber_jonnie]

It's not my area of expertise. It might be due to the tools being for little endian and 68000 being big endian?

Try it swapped, if it doesn't work try it not swapped.

You could very well be correct Alex.

...which is why I have created 2 versions..
one of them should work..

That said..I prefer to understand the process than just doing it blind..

OK so I think endianness is the issue here, and I'm struggling to remember when I was writing my own 27C4096's with 2.06 and Emutos that I wrote one and it didn't work, so that was £8 down the drain as it was an OTP IC, after which I bought stock of UV erasable 27C4096's.

Unless you have erasable ROMs, either electrically or UV I would get some before committing the image to ROM. Also if you want to change the version of Emutos later an OTP ROM isn't going to let you do that.

I can't find the backups of the images I actually used, but it may be on my Windows laptop I use in my workshop, I'll have a look, but I really don't remember if they were byteswapped or not.